Harry Potter is on the stage. I know, many of us would instinctively opt to serve the penal alternative. But look at the queues of hopefuls around the Palace Theatre in Shaftesbury Avenue and the initiates wearing their button badges promising not to give the ending away and soften your hearts. Potter studies have become as much a part of the British childhood as Swallows and Amazons or Enid Blyton.

In Harry Potter and the Cursed Child, the eighth instalment of the amiable chap’s hazardous journey through the world of Muggles, wizards and shape-shifting teachers, the scriptwriting team of J.K. Rowling and Jack Thorne introduce us to the main characters in adulthood. Mindful that the audience for a play in two parts and lasting five hours requires the stoicism of a Wagnerite, Cursed Child makes the themes of lost childhood, parental angst and fear of death and loss more central to the story than the page-turning novels. Much stage magic is sprinkled in the tale by John Tiffany, a Scottish director to watch, who directed another scary West End hit, Let the Right One In, as well as the National Theatre of Scotland’s riveting Iraq war saga Black Watch.

Harry, Hermione and Ron have evolved, as children do, into shape-shifted versions of their pre-pubescent selves. So Harry (Jamie Parker) is an exhausted dad with a day job at the Ministry of Magic: a bit like being stuck in the Department of Communities in terms of the wizarding greasy pole. There are neat touches for the Muggle parents to savour — Harry’s son Albus (Sam Clemmett) is unhappy and uneasy at Hogwarts, burdened by the family name. So is his quip-rich best mate Scorpius Malfoy (Anthony Boyle plays the dead-eyed, troubled adolescent, resorting to sarcasm to perfection). It is recognition that living up to parents, outstandingly good or evil, is a thorough pain.

Thankfully there is rich comedy to leaven post-Freudian insight. Hermione (Noma Dumezweni) has the unerring bossy diction of a grown-up public schoolgirl and has become Harry’s boss. No surprise there. Workplace feminism is compulsory now in the interpretation of children’s stories and J.K. could only have surprised us if Hermione had decided to be a stay-home mum. Gawky Ron (Paul Thornley) is one of those perpetual jokers, hiding his disappointments under a cloak of cheeriness — a slightly underdeveloped part overall here.

It’s all very Greek, in an am-I-doing-alright English way. Sons and fathers loop around each other’s ambitions and anxieties, unable to forge connections or break habits. Journeys and clocks reflect metaphysical odysseys. The theatrical challenge is making this entirety look enchanted, for a young audience accustomed to computer-generated film imagery. Old-fashioned prestidigitation comes to the fore, with an accomplished illusionist producing smoke from human ears and scarily realistic mechanical owls flapping across the stage. The magic is undercut with a wink to the parents paying for tickets. Those mundane chores we Muggle mums and dads nag on about are resolved by room-tidying spells and blitz-quick coups de theatre change kids in Gap casuals to blazered Hogwartians.